1. Field of the Invention
The invention concerns a device for detecting the state of rising of lumps of dough which are subjected to a proofing or fermenting process in a proofing chamber, for example induced by yeast, in the course of which the lumps of dough experience an increase in volume.
2. Description of the Related Art
The typical bakery products such as bread or rolls, which are sold daily in large quantities by branches or retail outlets of bakery factories, in order to be able to represent that they conform to the highest possible levels of freshness and quality, are baked in the respective branch or outlet locations, whereby it is also achieved that the produced amount can be flexibly adapted to the respective demand. Herein, for example, in the production of table rolls, the process begins with lumps of dough, which are pre-produced in a roll producing equipment in large number with substantially identical weight and volume. These lumps of dough, which are already subjected to yeast in their manufacture, are, prior to the rolls can be baked in an oven, subjected to a rising step in a proofing chamber, in which the size and dough consistency required for the baking of the rolls is strived for. Herein the proofing process is so carried out, with respect to the chamber temperature and in certain cases the dwell time, that during a total proofing time of approximately 20 minutes the necessary dough size is achieved, which in typical cases represents the five fold of the volume of the fresh xe2x80x9cgreenxe2x80x9d dough lumps produced on the roll producing device before the initiation of the rapidly occurring proofing process is set in motion therein by the elevation of the temperature, after the course of which, that is as soon as the dough lumps have achieved their desired size, these should be baked immediately, in order to achieve table rolls of standardized desired quality. The most important characteristic of quality of the finished baked rolls, which is associated in the mind of consumer with the image of quality, is the size thereof, which should also be uniform among the various types of rolls.
In order to achieve this uniformity, it would seem to be basically suitable to employ constant uniform conditions for carrying out the proofing process, for example using a computer program controlled time-wise control of the proofing chamber temperature, combined with an indication that the proofing time has concluded as determined by the temperature profile. Through such a temperature control it is however not possible to exclude influences on the size of the proofed dough lumps, which result from variations in yeast quality and/or variations in the introduction temperatures of the xe2x80x9cgreenxe2x80x9d dough lumps, and which can lead to significant size variations of the proofed dough lumps. It is thus necessary, even when employing a uniform time controlled proofing of the dough lumps, to subject the dough lumps treated in the proofing chamber to a visual quality control before they can be introduced into the baking oven, which however demands a high level of practical experience, in particular in that respect of how in certain cases a proofing process is to be carried out up to suitable ripeness of the dough lumps. The sales persons employed in the branches, which may have only limited knowledge of the baking process, do not as a rule have this particular necessary experience. This has the consequence that often it is only after the table rolls have been baked that it can be recognized whether these satisfy the required quality characteristics.
It is thus the task of the invention to provide a device of the above described type, which makes possible a reliable, objective measurement of the respective proofing condition of the dough lumps, which correlates to their desired final size.
This task is inventively solved thereby, that a distance sensor operating on a contactless measurement principle is provided in association with at least one of the dough lumps provided in the proofing chamber, which at least then, when the thickness of the dough lump achieves a predetermined desired value, which is associated with the intended condition of proofing of the dough lump, produces a signal which is characteristic therefore.
The inventive device is based on the fact that the volume increase, which the dough lump experiences through the proofing process, seen from its center of gravity, leads to a dimensional enlargement in every direction, so that by measurement of the distance or separation of a surface point or area of the dough lump from the position at which the sensor is situated, a very reliable determination of the volume of the dough lump, or its proofing ripeness condition, is made possible. Starting with an absolute measurement of the starting distance as reference value, and with the progressive measurement of the reduction of this separation, the volume of the dough lump is determinable with sufficient precision, so that from such a distance measurement a sufficiently precise indication with respect to the ripeness of the dough lump can be determined.
By means of the invention the objective determination of the condition of ripeness of the monitored dough lump is made possible in a simple manner, and therewith also that of other dough lumps identical to this dough lump. The inventive device makes possible at the same time an automatic monitoring of the proofing process and in certain cases also permits, depending upon the instantaneously detected volume of the dough lumps, to control the proofing process by influencing the proofing chamber temperature in such a manner, so that the condition of ripeness necessary for the subsequent baking process of the dough lumps is achieved after the expiration of a pre-determined time span. The inventive device is suitable for avoiding inaccurate determinations of the condition of ripeness of the dough lumps and therewith makes possible the rational production of baked wares in a branch or chain operation.
In a preferred design of the inventive device the distance sensor thereof is arranged and oriented in such a manner that it measures the height of the dough lump, in the central area thereof, over the sheet or support, which is useful as a measuring value for the reason that it is determinable in relation to a fixed pre-determined reference value, namely the distance of the support for the dough lumps to the distance sensor, which is pre-determined by the construction specifications of the proofing chamber. Further, the vertical thickness of a dough lump during the proofing process, even in the case that this is smaller than the largest horizontal cross-section, will change a greater amount than measurable by a xe2x80x9chorizontalxe2x80x9d distance measurement of the horizontal radius of the dough lump, since the vertical thickness change is comprised of the sum of the distance change from the center point of the dough lump to the support plus the change in the vertical separation from the dough lump upper surface to the center point of the dough lump.
A suitable distance sensor to be realized for the inventive device could for example be in the manner of a distance measuring and adjusting system of an auto-focus camera, or an optoelectronic distance measuring device, which however because of the required optical imaging of the target or measurement object is associated with a substantial space requirement, which would be acceptable only in the case of a fixed installation in a chamber with high capacity.
In a preferred design of the inventive device the distance sensor is thus designed as an ultrasonic sensor, which works on the principle of the elapsed travel time measurement of the ultrasonic signal. A distance sensor of this type only requires a small amount of space and can be installed without complication between two support surfaces for dough lumps within a proofing chamber, so that sufficient space for the monitored dough lump still remains below the sensor.
In accordance therewith the distance sensor can be provided on a framework which can be set up on the floor inside a conventional proofing chamber, preferably a three legged framework, and insofar is suitable as a retrofit component for existing proofing cabinets.
As distance sensor a light interruption device is also suitable, in which a light beam is interrupted as soon as at least one of the dough lumps achieves a height that is characteristic for a desired degree of ripeness.
A light interruption device is preferably fixedly installed in the proofing cabinet, wherein the light source and the light detector can be built into the proofing cabinet walls preferably in such a manner, that the light detector is height adjustable, wherein the height adjustability can be realized in simple manner thereby, that the light source is height adjustable and a receiver line is provided fixed in the chamber, comprised of a number of light detectors arranged in small vertical separation from each other, or a single receiver with receiver surface extending in the vertical direction, as well as a gate or aperture which is adjustable in height to a pre-determined distance above the floor which carries the dough lumps.
In a preferred design of such a light detector the detector light beam is so arranged that it crosses over multiple dough lumps, for example a centrally oriented row of dough lumps, whereby even in the case of a minor irregular arrangement of the dough lumps the probability is increased that the light detector is interrupted at the correct point in time, even when the light detector-light beam does not precisely cross over the central plane of some of the individual dough lumps.
In one embodiment of the distance measuring device as a light detector device, it is particularly advantageous when a laser is employed as a light source, which emits a strongly bundled parallel light beam of small cross-section and high light intensity without requirement for specialized optical elements and/or apertures, which in an advantageous embodiment of the invention can be divided by means of a simple beam splitter into multiple partial light beams of preferably approximately the same intensity, which can be utilized for monitoring of dough lumps in multiple planes of a proofing chamber or even for monitoring of dough lumps in multiple proofing chambers, which are positioned in spatially fixed coordinates within a larger proofing facility, in which the employment of a laser can be more economical than an arrangement of light detectors which have respectively one individual light source of simple design.
The reliability of recognition of the interruption of a light interruption device in accordance with a further embodiment of the invention is thereby improved, in that at least one scatter-light detector is provided, preferably in a device above the sensor plane defined by the light interruption device, wherein the scatter-light detector produces a signal, when the light shutter interrupting areas of a dough lump are illuminated by the light interruption device light beam and thereby scatter light, which is easy to construct by means of a simple imaging system uniformly monitoring the dough lumps, and which by using a light detector can be utilized for producing a confirmation signal.